Research And Application Of Melt-spinning Dynamics Of Fine Denier Hollow Polyester (PET) Staple Fiber

It is important for chemical fiber industry to develop differential polyester(PET) fiber.Recently,hollow PET staple fiber,which has the sound properties of softness, smoothness and heat retention,has attracted much attention of many chemical fiber plants according to the need of market and consumer.Because of the hardness of both fine denier and hollowness requirement,it is difficult to resolve producing problems only by working experience.Now,computer simulation provides an alternative efficient way of solving engineering problems.In this paper we consider the relation between spinning conditions and product properties by cooperating melt-spinning PET fiber dynamics and computer technique.It is expected to be useful for practical melt-spinning process.On the basis of melt-spinning dynamics process,the fundamental equations, such as momentum equation,energy equilibrium,governing equation and orientation equation have been selected.Both equation parameters and PET material structure parameters were fitted.Then monofilament spinning model and multifilament spinning model of melt-spinning fine denier hollow PET fiber have been established cooperating hollow fiber geometry and hole number and distribution of spinneret.The established models describing melt-spinning fine denier hollow PET fiber were solved by the fourth order Runge-Kutta algorithm.The fiber hollowness,outer radius,velocity and tension along spinning line as well as the distribution of hollowness and initial tension were computed.The effects of mass throughput, intrinsic viscosity,spinning velocity,spinning temperature and quench air conditions on hollow fiber properties have been considered.It can be concluded that the hollowness of as-spun fiber drastically increases with the increase of quench air conditions,mass throughput and intrinsic viscosity and the decrease of spinning temperature;however,hollowness hardly increases with the increase of spinning velocity.Furthermore,the hollowness and vitrification point of as-spun fiber at different layers have been analyzed.The simulation results and experimental data are agreed well.The research results offered us an effective way to develop 1.56dtex×38mm fine denier hollow PET staple fiber.Meanwhile,we proposed the mathematic relation between initial tension(F₀₀) and spinning conditions in order to improve the computing efficiency.Based on the established simulation model and 2000t/a differential fiber spinning device of SINOPEC Tianjin Company,we successfully developed and produced 1.56 dtex×38mm fine denier hollow PET staple fiber.The final product properties,such as hollowness of 19.1%,average denier of 1.61dtex,denier deviation of 3.2%,average length of 38.7mm,length deviation of 1.8%,breaking strength of 6.14cN/dtex, breaking elongation percentage of 22.5%are sound and can meet the demand of consumer.It can be found that the measured hollowness deviation by cross-section image is higher than the simulated data.The reason may be contributed to cross-blowing condition and single-side oiling.The relation between later process and properties of hollow fiber PET staple fiber is needed to be explored in the future research.